Problem: $-\dfrac{8}{12} + \dfrac{2}{8} = {?}$
Answer: $ = - {\dfrac{8 \times 2}{12 \times 2}} + {\dfrac{2 \times 3}{8 \times 3}} $ $ = - {\dfrac{16}{24}} + {\dfrac{6}{24}} $ $ = - \dfrac{{16} + {6}}{24} $ $ = -\dfrac{10}{24}$